U.S. patent application number 15/312743 was filed with the patent office on 2017-06-29 for elastic infill for artificial turf.
The applicant listed for this patent is Fine Chemical Co., Ltd.. Invention is credited to Sung Yull LEE.
Application Number | 20170183830 15/312743 |
Document ID | / |
Family ID | 52290744 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170183830 |
Kind Code |
A1 |
LEE; Sung Yull |
June 29, 2017 |
ELASTIC INFILL FOR ARTIFICIAL TURF
Abstract
Provided is an elastic infill for artificial turf. The elastic
infill is produced by pelletization of an elastomer composition
comprising a silane coupling agent and a mixture of an olefin
copolymer-containing base resin and an inorganic filler. The silane
coupling agent is present in admixture with the mixture.
Alternatively, the silane coupling agent may be grafted onto the
olefin copolymer to allow cross-linking of the olefin copolymer in
the presence of water.
Inventors: |
LEE; Sung Yull; (Busan,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fine Chemical Co., Ltd. |
Gimhae-si |
|
KR |
|
|
Family ID: |
52290744 |
Appl. No.: |
15/312743 |
Filed: |
March 6, 2015 |
PCT Filed: |
March 6, 2015 |
PCT NO: |
PCT/KR2015/002183 |
371 Date: |
November 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 15/00 20130101;
C08L 23/00 20130101; C08L 2312/08 20130101; C08F 255/026 20130101;
C08K 5/54 20130101; C08F 255/026 20130101; C08F 255/02 20130101;
C08F 230/08 20130101; C08F 230/08 20130101; C08F 287/00 20130101;
C08F 255/02 20130101; E01C 13/08 20130101; C08F 287/00 20130101;
C08K 3/00 20130101; C08L 23/16 20130101; C08F 230/08 20130101 |
International
Class: |
E01C 13/08 20060101
E01C013/08; C08L 15/00 20060101 C08L015/00; C08L 23/16 20060101
C08L023/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2014 |
KR |
10-2014-0075905 |
Claims
1. An elastic infill for artificial turf that is produced by
pelletization of an elastomer composition comprising: a silane
coupling agent and a mixture of an olefin copolymer-containing base
resin and an inorganic filler, wherein the silane coupling agent is
present in admixture with the mixture or is grafted onto the olefin
copolymer to allow cross-linking of the olefin copolymer in the
presence of water.
2. The elastic infill for artificial turf according to claim 1,
wherein the olefin copolymer is a copolymer of i) ethylene and ii)
at least one ethylenically unsaturated monomer selected from the
group consisting of C.sub.3-C.sub.10 .alpha.-monoolefins,
C.sub.1-C.sub.12 alkyl esters of C.sub.3-C.sub.20 monocarboxylic
acids, unsaturated C.sub.3-C.sub.20 mono- or dicarboxylic acids,
anhydrides of unsaturated C.sub.4-C.sub.8 dicarboxylic acids, and
vinyl esters of saturated C.sub.2-C.sub.18 carboxylic acids.
3. The elastic infill for artificial turf according to claim 1,
wherein the olefin copolymer is an olefin/.alpha.-olefin (OAO)
copolymer.
4. The elastic infill for artificial turf according to claim 3,
wherein the olefin is ethylene or propylene and the .alpha.-olefin
is an olefin consisting of three or more carbon atoms and having a
terminal carbon-carbon double bond.
5. The elastic infill for artificial turf according to claim 3,
wherein the olefin/.alpha.-olefin copolymer is an olefin random
copolymer.
6. The elastic infill for artificial turf according to claim 5,
wherein the olefin random copolymer is a random copolymer of
ethylene or propylene and at least one copolymeric .alpha.-olefin
comonomer.
7. The elastic infill for artificial turf according to claim 3,
wherein the olefin/.alpha.-olefin copolymer is an olefin block
copolymer.
8. The elastic infill for artificial turf according to claim 7,
wherein the olefin block copolymer is a multi-block copolymer which
comprises ethylene and one or more copolymerizable .alpha.-olefin
comonomers in a polymerized form and has a plurality of blocks or
segments of two or more polymerized monomer units having different
chemical or physical properties.
9. The elastic infill for artificial turf according to claim 1,
wherein the base resin further comprises a rubber selected from the
group consisting of natural rubbers, synthetic rubbers, and
combinations thereof.
10. The elastic infill for artificial turf according to claim 1,
wherein the rubber is present in an amount of 5 to 50 parts by
weight, based on 100 parts by weight of the olefin copolymer.
11. The elastic infill for artificial turf according to claim 1,
wherein the silane coupling agent is an alkoxysilane compound.
12. The elastic infill for artificial turf according to claim 1,
wherein the silane coupling agent is present in an amount of 0.5 to
20 parts by weight, based on 100 parts by weight of the base
resin.
13. The elastic infill for artificial turf according to claim 1,
wherein the elastic infill has a compression set of 2 to 20% at
room temperature and 15 to 40% at 70.degree. C., as measured based
on ASTM D395.
14. A method for producing an elastic infill for artificial turf,
comprising: providing an elastomer composition comprising a silane
coupling agent and a mixture of an olefin copolymer-containing base
resin and an inorganic filler; kneading the elastomer composition;
and extruding and pelletizing the kneaded elastomer
composition.
15. The method for producing an elastic infill for artificial turf
according to claim 14, further comprising heating the pelletized
elastic infill in water to cross-link the elastic infill.
16. The method for producing an elastic infill for artificial turf
according to claim 14, further comprising placing the pelletized
elastic infill under ambient conditions for cross-link of the
elastic infill in the presence of water.
17. The method for producing an elastic infill for artificial turf
according to claim 14, wherein the elastomer composition further
comprises at least one additive selected from the group consisting
of initiators, catalysts, processing aids, resin stabilizers, and
pigments.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to an elastic infill for
artificial turf, and more specifically to a highly heat resistant
elastic infill for artificial turf.
BACKGROUND ART
[0002] Artificial turf feels like natural grass, can be used for a
prolonged period of time, requires low maintenance cost, and is
cushiony enough to prevent injury. Due to these advantages,
artificial turf has been increasingly installed on sports fields
across the world. Most of the currently used artificial turf
products are of a carpet type and have a structure in which rubber
chips and sand are filled to impart a texture similar to that of
natural grass. However, the use of waste tire rubber chips as
artificial turf infills has become a social issue because of their
hazards to human health and environment. Due to their black color,
waste tire rubber chips tend to absorb sunlight and increase the
temperature of playgrounds, resulting in deterioration of the
exercise environment. At temperatures exceeding 30.degree. C. in
summer, rubber chips produce an acrid smell and are often melted on
the hot ground and stuck to the bottoms of players' shoes. Since
waste tire chips are produced by pulverization, they become brittle
after long-term use and produce dust, which is a cause of
environmental pollution. The detection of harmful substances,
including heavy metals, polynuclear aromatic hydrocarbons, toluene,
benzene, and nitrosamines, in artificial turf products was reported
in some European countries. Under these circumstances, there is a
growing need for new artificial turf infills that have the
potential to replace waste tire chips.
DETAILED DESCRIPTION OF THE INVENTION
[0003] According to one aspect of the present invention, there is
provided an elastic infill for artificial turf that is produced by
pelletization of an elastomer composition comprising a silane
coupling agent and a mixture of an olefin copolymer-containing base
resin and an inorganic filler wherein the silane coupling agent is
present in admixture with the mixture or is grafted onto the olefin
copolymer to allow cross-linking of the olefin copolymer in the
presence of water.
[0004] According to a further aspect of the present invention,
there is provided a method for producing an elastic infill for
artificial turf, including: providing an elastomer composition
including a silane coupling agent and a mixture of an olefin
copolymer-containing base resin and an inorganic filler; kneading
the elastomer composition; and extruding and pelletizing the
kneaded elastomer composition.
MODE FOR CARRYING OUT THE INVENTION
[0005] Rubber chips produced by cross-linking EPDM rubbers are
currently used instead of harmful waste tire chips. The production
of the rubber chips requires pulverization of the cross-linked
rubbers. However, the chips produce dust that tends to scatter
after construction. Further, the surface morphology of the rubber
chips is irregular, leaving unnecessary spaces therebetween. The
spaces disperse the cohesion between the rubber chips, making it
impossible for the rubber chips to properly support turf.
[0006] Korean Patent No. 10-0799262 describes an environmentally
friendly infill composition for artificial turf which includes a
styrene-ethylene. butadiene-styrene (SEBS) resin, an olefinic
elastomer, a mineral oil, an inorganic filler, a weathering
stabilizer, and an inorganic pigment. This patent introduces the
production of pellet-shaped chips by extrusion rather than by
pulverization. Advantageously, the chips produce no dust after
construction. However, the infill composition is not suitable for
use in an artificial turf infill from an economic viewpoint because
the SEBS resin is at least twice more expensive than general
rubbers and polyolefin elastomers. Accordingly, the use of the
expensive SEBS resin limits the marketability of the infill
composition. An olefinic elastomer may be used in admixture with
the SEBS resin. This contributes to a reduction in material cost
but causes poor heat resistance and reduced elastic recovery of an
infill of the infill composition due to the low melting point of
the olefinic elastomer. As a result, there is a risk that
artificial turf using the infill will undergo deformation and the
pellets will agglomerate over a long period of time after
construction. Thus, there is a need for an improved elastic infill
for artificial turf.
[0007] A detailed description will be given of the present
disclosure.
[0008] According to one embodiment, the elastic infill for
artificial turf is produced by pelletizing an elastomer composition
comprising a silane coupling agent and a mixture of an olefin
copolymer-containing base resin and an inorganic filler. In this
embodiment, the silane coupling agent is present in admixture with
the mixture or is grafted onto the olefin copolymer to allow
cross-linking of the olefin copolymer in the presence of water.
[0009] In one embodiment, the olefin copolymer may be an ethylene
copolymer. The ethylene copolymer may be a copolymer of i) ethylene
and ii) at least one ethylenically unsaturated monomer selected
from the group consisting of C.sub.3-C.sub.10 .alpha.-monoolefins,
C.sub.1-C.sub.12 alkyl esters of C.sub.3-C.sub.20 monocarboxylic
acids, unsaturated C.sub.3-C.sub.20 mono- or dicarboxylic acids,
anhydrides of unsaturated C.sub.4-C.sub.8 dicarboxylic acids, and
vinyl esters of saturated C.sub.2-C.sub.18 carboxylic acids.
[0010] The ethylene copolymer may be a soft polymer having a Shore
A hardness between 40 and 95. The ethylene copolymer is the most
suitable polymer that meets the requirements of the elastic infill
in terms of oxidation resistance, weather resistance, elasticity,
and price.
[0011] Specific examples of ethylene copolymers suitable for use in
the elastic infill include ethylene vinyl acetate (EVA), ethylene
butyl acrylate (BA), ethylene methyl acrylate (EMA), ethylene ethyl
acrylate (EEA), ethylene methyl methacrylate (EMMA), ethylene
butene copolymers (EB-Co), and ethylene octene copolymers
(EO-Co).
[0012] In one embodiment, the olefin copolymer may be an
olefin/.alpha.-olefin (OAO) copolymer. The term
"olefin/.alpha.-olefin copolymer" used herein generally refers to a
copolymer including ethylene or propylene and an .alpha.-olefin
having two or more carbon atoms. The .alpha.-olefin is an olefin
consisting of at least two carbon atoms and having a terminal
carbon-carbon double bond.
[0013] Preferably, ethylene or propylene makes up the largest mole
fraction of the polymer. Specifically, ethylene or propylene
accounts for about 50 mole % or more of the polymer. More
preferably, ethylene or propylene accounts for about 60 mole % or
more, about 70 mole % or more or about 80 mole % or more of the
polymer. The substantial remainder of the polymer includes one or
more other comonomers. The comonomers are preferably
.alpha.-olefins having three or more carbon atoms. The
olefin/.alpha.-olefin copolymer may be an ethylene/octene
copolymer. In this case, the polymer includes about 80 mole % or
more of ethylene and about 10 to about 20 mole %, preferably about
15 to about 20 mole % of octene.
[0014] The olefin/.alpha.-olefin copolymer may be a random or block
copolymer. Representative examples of OAO copolymers include
ethylene alpha olefin (EAO) copolymers and propylene alpha olefin
(PAO) copolymers. Many products are commercially available for the
olefin/.alpha.-olefin copolymer. Suitable EAO copolymers include
ENGAGE and INFUSE from Dow Chemical, TAFMER from Mitsui, EXACT from
Exxon Mobile, and LG-POE from LG Chem. Suitable PAO copolymers
include VERSIFY from Dow Chemical, NOTIO from Mitsui, and VISTAMAXX
from Exxon Mobile.
[0015] In one embodiment, the olefin/.alpha.-olefin copolymer used
in the artificial turf infill is an olefin block copolymer (OBC).
The olefin block copolymer (OBC) is a multi-block copolymer. The
multi-block copolymer refers to a polymer including two or more
chemically distinct zones or segments (also called "blocks") that
are preferably bonded in a linear configuration, i.e. a polymer
including chemically distinguished units that are bonded end-to-end
to polymerized ethylenic or propylenic functional groups rather
than in a pendant or graft configuration.
[0016] The olefin block copolymer (OBC) refers to an
ethylene/.alpha.-olefin multi-block copolymer or a
propylene/.alpha.-olefin multi-block copolymer. The olefin block
copolymer includes ethylene or propylene and one or more
copolymerizable .alpha.-olefin comonomers in a polymerized form.
The olefin block copolymer is characterized by the presence of a
plurality of blocks or segments of two or more polymerized monomer
units having different chemical or physical properties.
[0017] In some embodiments, the multi-block copolymer may be
represented by the following formula:
(AB)n
[0018] wherein n is an integer of at least 1, preferably an integer
greater than 1, for example, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50,
60, 70, 80, 90, 100 or higher, A represents a hard block or
segment, and B represents a soft block or segment. Preferably, A
and B are linked in a linear configuration rather than in a
branched or star configuration. The hard segment refers to a block
of polymerized units in which ethylene or propylene is present in a
particular amount. In some embodiments, the ethylene or propylene
content of the hard segment is 95% by weight or more. In further
embodiments, the ethylene or propylene content of the hard segment
is 98% by weight or more. That is, in some embodiments, the content
of the comonomers in the hard segment is not greater than 5% by
weight. In further embodiments, the content of the comonomers in
the hard segment is not greater than 2% by weight. In some
embodiments, the hard segment is wholly or substantially composed
of ethylene or propylene. Meanwhile, the soft segment refers to a
block of polymerized units in which the comonomers are present in a
particular amount. In some embodiments, the content of the
comonomers in the soft segment is 5% by weight or more. In further
embodiments, the content of the comonomers in the soft segment is
8% by weight or more, 10% by weight or more, or 15% by weight or
more. In further embodiments, the content of the comonomers in the
soft segment is 20% by weight or more, 25% by weight or more, 30%
by weight or more, 35% by weight or more, 40% by weight or more,
45% by weight or more, 50% by weight or more, or 60% by weight or
more.
[0019] In one embodiment, the olefin block copolymer may have a
density of 0.85 g/cc to 0.91 g/cc or 0.86 g/cc to 0.88 g/cc.
[0020] In one embodiment, the olefin block copolymer may have a
melt index (MI) of 0.01 g/10 minutes to 30 g/10 minutes, 0.01 g/10
minutes to 20 g/10 minutes, 0.1 g/10 minutes to 10 g/10 minutes,
0.1 g/10 minutes to 5.0 g/10 minutes, or 0.1 g/10 minutes to 1.0
g/10 minutes, as measured by ASTM D1238 (190.degree. C., 2.16
kg).
[0021] In one embodiment, the olefin block copolymer produced in a
continuous process may have a polydispersity index (PDI) of 1.7 to
3.5, 1.8 to 3, 1.8 to 2.5, or 1.8 to 2.2. The olefin block
copolymer produced in a batch or semi-batch process may have a PDI
of 1.0 to 3.5, 1.3 to 3, 1.4 to 2.5, or 1.4 to 2.
[0022] In one embodiment, the olefin block copolymer may contain 5
to 30% by weight, 10 to 25% by weight, or 11 to 20% by weight of
the hard segment. The hard segment may contain 0.0 to 0.9% by mole
of units derived from the comonomers. The olefin block copolymer
may contain 70 to 95% by weight, 75 to 90% by weight, or 80 to 89%
by weight of the soft segment. The soft segment may contain less
than 15% by mole or 9 to 14.9% by mole of units derived from the
comonomers. In one embodiment, the comonomer may be butene or
octene.
[0023] The olefin block copolymer has a chain structure in which
blocks of hard and soft segments are arranged alternately. Due to
this chain structure, the olefin block copolymer has both stiffness
of the hard segments and flexibility of the soft segments, which
are responsible for its high heat resistance compared to that of
ethylene random copolymers with similar hardness and its comparable
elastic recovery to styrenic or vulcanized olefinic thermoplastic
elastomers. In addition, the olefin block copolymer causes no dust
and environmental problems and is advantageous in terms of price
over styrenic elastomer mixtures.
[0024] The olefin/.alpha.-olefin copolymer used in the elastic
infill is an olefin random copolymer (ORC), which is preferred
because of its very low price.
[0025] The olefin random copolymer may be a random copolymer of
ethylene or propylene and at least one copolymerizable
.alpha.-olefin comonomer.
[0026] The ORC may be a copolymer of ethylene and an
.alpha.-olefin, i.e. an EAO copolymer. In this case, the ORC may
contain at least one copolymer of a C.sub.3-C.sub.20
.alpha.-olefin, a C.sub.3-C.sub.12 .alpha.-olefin or a
C.sub.3-C.sub.8 .alpha.-olefin. A suitable .alpha.-olefin may be
straight chained or branched (for example, substituted with at
least one C.sub.1-C.sub.3 alkyl or aryl group). Specific examples
of such .alpha.-olefins include propylene, butene,
3-methyl-1-butene, 3,3-dimethyl-1-butene, pentene, pentene
substituted with at least one methyl, ethyl or propyl group, hexene
substituted with at least one methyl, ethyl or propyl group,
heptene substituted with at least one methyl, ethyl or propyl
group, octene substituted with at least one methyl, ethyl or propyl
group, nonene substituted with at least one methyl, ethyl or propyl
group, decene substituted with at least one ethyl, methyl or
dimethyl group, dodecene substituted with at least one ethyl,
methyl or dimethyl group, and styrene substituted with at least one
ethyl, methyl or dimethyl group. Particularly preferred
.alpha.-olefin comonomers are propylene, butene (e.g., 1-butene),
hexene, and octene (e.g., 1-octene or 2-octene). The ethylene
content of the copolymer may be from 60 mole % to 99.5 mole %. In
some embodiments, the ethylene content may be from 80 mole % to 99
mole %. In some embodiments, the ethylene content may be from 85
mole % to 98 mole %. Accordingly, the .alpha.-olefin content of the
copolymer may be limited to the range of 0.5 mole % to 40 mole %.
In some embodiments, the .alpha.-olefin content may be limited to
the range of 1 mole % to 20 mole %. In some embodiments, the
.alpha.-olefin content may be limited to the range of 2 mole % to
15 mole %. The distribution of the .alpha.-olefin comonomer is
typically random and is uniform over different molecular weight
fractions of the ethylene copolymer.
[0027] The ORC may be a copolymer of propylene and an
.alpha.-olefin, i.e. a PAO copolymer. In this case, the ORC may
contain at least one copolymer of a C.sub.2-C.sub.20
.alpha.-olefin, a C.sub.2-C.sub.12 .alpha.-olefin or a
C.sub.2-C.sub.8 .alpha.-olefin. A suitable .alpha.-olefin may be
straight chained or branched (for example, substituted with at
least one C.sub.1-C.sub.3 alkyl or aryl group). Specific examples
of such .alpha.-olefins include ethylene, butene,
3-methyl-1-butene, 3,3-dimethyl-1-butene, pentene, pentene
substituted with at least one methyl, ethyl or propyl group, hexene
substituted with at least one methyl, ethyl or propyl group,
heptene substituted with at least one methyl, ethyl or propyl
group, octene substituted with at least one methyl, ethyl or propyl
group, nonene substituted with at least one methyl, ethyl or propyl
group, decene substituted with at least one ethyl, methyl or
dimethyl group, dodecene substituted with at least one ethyl,
methyl or dimethyl group, and styrene substituted with at least one
ethyl, methyl or dimethyl group. Particularly preferred
.alpha.-olefin comonomers are ethylene, butene (e.g., 1-butene),
hexene, and octene (e.g., 1-octene or 2-octene). The propylene
content of the copolymer may be from 60 mole % to 99.5 mole %. In
some embodiments, the propylene content may be from 80 mole % to 99
mole %. In some embodiments, the propylene content may be from 85
mole % to 98 mole %. Accordingly, the .alpha.-olefin content of the
copolymer may be limited to the range of 0.5 mole % to 40 mole %.
In some embodiments, the .alpha.-olefin content may be limited to
the range of 1 mole % to 20 mole %. In some embodiments, the
.alpha.-olefin content may be limited to the range of 2 mole % to
15 mole %. The distribution of the .alpha.-olefin comonomer is
typically random and is uniform over different molecular weight
fractions of the propylene copolymer.
[0028] The density of the ethylene/.alpha.-olefin (EAO) copolymer
or the propylene/.alpha.-olefin (PAO) copolymer may be a function
of the length and amount of the .alpha.-olefin. That is, as the
chain length and amount of the .alpha.-olefin increases, the
density of the copolymer decreases. Generally, the copolymer can
better retain a three-dimensional structure at a higher density and
can have better elastomeric properties at a lower density.
[0029] The ORC may have a density of 0.86 to 0.90 g/cc. In some
embodiment, the ORC may have a density of 0.861 to 0.89 g/cc. In
some embodiment, the ORC may have a density of 0.862 to 0.88
g/cc.
[0030] The silane coupling agent present in the elastomer
composition is grafted onto the olefin copolymer in the presence of
a radical initiator present in the composition and allows
cross-linking of the olefin copolymer in the presence of water. Due
to the presence of the silane coupling agent in the elastomer
composition, the elastic infill produced by pelletization of the
elastomer composition can be cross-linked when heated in water in a
subsequent processing step. Alternatively, the elastic infill may
be constructed in artificial turf without further processing after
pelletization of the composition. In this case, the elastic infill
can absorb moisture from air and be cross-linked in nature over
time.
[0031] The silane coupling agent is chemically bound to the base
resin to form a silane grafted copolymer and serves as functional
groups for the cross-linking of the elastic infill after
pelletization. The silane coupling agent may be an alkoxysilane
compound. Examples of suitable alkoxysilane compounds include
vinyltrimethoxysilane, vinyltriethoxysilane, tetraethoxysilane,
tetra-n-propoxysilane, methyltriethoxysilane,
methyltrimethoxysilane, methyltri(2-methoxyethoxy)silane,
3-methacryloyloxypropyltrimethoxysilane,
3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane,
and 3-glycidyloxypropyltrimethoxysilane. These silane coupling
agents may be used alone or in combination of two or more
thereof.
[0032] The degree of cross-linking of the elastic infill may be
adjusted depending on the amount of the silane coupling agent in
the elastomer composition.
[0033] In the elastic infill of the present invention, the content
of the silane coupling agent is from 0.5 to 5 parts by weight,
preferably from 0.8 to 3 parts by weight, more preferably from 1 to
2 parts by weight, based on 100 parts by weight of the base resin.
If the silane coupling agent is present in an amount of less than
the lower limit defined above, the elastic infill may not be
effectively cross-linked, resulting in insufficient heat
resistance. As a result, the elastic infill tends to agglomerate at
high temperatures in summer. Meanwhile, if the silane coupling
agent is present in an amount exceeding the upper limit defined
above, the cross-linking density of the elastic infill does not
increase above a predetermined level, which is economically
undesirable.
[0034] The formation of the silane grafted copolymer requires the
presence of a radical polymerization initiator in the elastomer
composition. The radical polymerization initiator serves to induce
chemical grafting the silane coupling agent onto the base resin. As
the radical polymerization initiator, there may be used, for
example, t-butyl cumyl peroxide, benzoyl peroxide, cumene
hydroperoxide, dicumyl peroxide, t-butyl peroxybenzoate, t-butyl
peroxyisopropyl carbonate, t-butyl peroxylaurylate, t-butyl
peroxyacetate, di-t-butyl peroxyphthalate, t-dibutyl peroxymaleate,
cyclohexanone peroxide, t-butylcumyl peroxide, t-butyl
hydroperoxide, 1,3-bis(t-butylperoxyisopropyl)benzene, methyl ethyl
ketone peroxide, 2,5-dimethyl-2,5-di(benzoyloxy)hexane,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide,
2,5-dimethyl-2,5-(t-butylperoxy)-3-hexane,
n-butyl-4,4-bis(t-butylperoxy)valerate,
.alpha.,.alpha.'-bis(t-butylperoxy)diisopropylbenzene or a mixture
thereof.
[0035] The elastomer composition may optionally further include a
catalyst to shorten the time required for cross-linking of the
elastic infill in the presence of water on the grafting step.
Examples of suitable catalysts include dibutyltin dilaurate,
dibutyltin dimaleate, dibutyltin diacetate, dioctyltin maleate,
dibutyltin dioctoate, tetrabutyl titanate, hexylamine, dibutylamine
acetate, tin octoate (tin (II) 2-ethylhexanoate), lead naphthenate,
zinc caprylate, and cobalt naphthenate.
[0036] The catalyst may be present in an amount of 0.05 to 1 part
by weight, preferably 0.1 to 0.7 part by weight, based on 100 parts
by weight of the base resin. The presence of the catalyst in an
amount of less than the lower limit defined above leads to slow
cross-linking, and as a result, more energy and time is required
for cross-linking. Meanwhile, the presence of the catalyst in an
amount exceeding the upper limit defined above does not contribute
to further improvement of cross-linking rate.
[0037] The inorganic filler serves to increase the specific gravity
of the infill after construction in artificial turf so that the
infill is prevented from being swept away even during heavy
rainfall. The inorganic filler is added for the purpose of
preventing the infill from being thermally deformed. Examples of
such inorganic fillers include calcium carbonate (CaCO.sub.3),
talc, mica, clay, silica (SiO.sub.2), barium sulfate (BaSO.sub.4),
and magnesium carbonate (MgCO.sub.3). These inorganic fillers may
be used alone or in combination. Calcium carbonate is most
preferred because its low price. The inorganic filler may be used
in an amount of 50 to 500 parts by weight, preferably 80 to 400
parts by weight, based on 100 parts by weight of the base resin.
The use of the inorganic filler in an amount of less than 50 parts
by weight leads to a low specific gravity of the elastic infill,
increasing the risk that the elastic infill may be swept away by
rain. Meanwhile, the use of the inorganic filler in an amount of
more than 500 parts by weight may excessively increase the hardness
of the elastic infill, cause loss of elasticity of the elastic
infill, and excessively reduce the strength of the elastic infill,
increasing the risk that the elastic infill may be readily broken,
for example, when players slide on artificial turf during their
play time.
[0038] The base resin used in the elastic infill of the present
invention may further include a rubber selected from the group
consisting of natural rubbers, synthetic rubbers, and combinations
thereof. The rubber is added for the purpose of supporting the
performance of the olefin copolymer or reducing the production cost
of the elastic infill. The amount of the rubber is limited to a
predetermined range.
[0039] The natural rubber may be a general natural rubber or a
modified natural rubber. The general natural rubber may be one of
those known in the art. No particular limitation is imposed on the
specification (e.g., the country of origin) of the general natural
rubber. The natural rubber includes cis-1,4-polyisoprene as a major
component. Alternatively, the natural rubber may also include
trans-1,4-polyisoprene depending on required characteristics. For
example, the natural rubber may be balata, which is a latex
obtained from trees of the Sapotaceae family indigenous to South
America. Balata includes trans-1,4-polyisoprene as a major
component. The modified natural rubber refers to a rubber produced
by modifying or purifying the general natural rubber. As the
modified natural rubber, there may be exemplified epoxidized
natural rubber (ENR), deproteinized natural rubber (DPNR), or
hydrogenated natural rubber.
[0040] The synthetic rubber may be selected from the group
consisting of styrene butadiene rubber (SBR), modified styrene
butadiene rubber, butadiene rubber (BR), modified butadiene rubber,
chlorosulfonated polyethylene rubber, epichlorohydrin rubber,
fluorine rubber, silicone rubber, nitrile rubber, hydrogenated
nitrile rubber, nitrile butadiene rubber (NBR), modified nitrile
butadiene rubber, chlorinated polyethylene rubber, styrene
butadiene styrene (SBS) rubber, styrene ethylene butylene styrene
(SEBS) rubber, styrene isoprene styrene (SIS) rubber, ethylene
propylene rubber, ethylene propylene diene (EPDM) rubber, hypalon
rubber, chloroprene rubber, ethylene vinyl acetate rubber, acrylic
rubber, hydrin rubber, vinylbenzyl chloride styrene butadiene
rubber, bromomethyl styrene butyl rubber, maleated styrene
butadiene rubber, carboxylated styrene butadiene rubber, epoxy
isoprene rubber, maleated ethylene propylene rubber, carboxylate
nitrile butadiene rubber, brominated polyisobutyl
isoprene-co-paramethyl styrene (BIMS) rubber, vulcanized olefinic
thermoplastic elastomers, and combinations thereof.
[0041] The rubber is preferably a styrenic thermoplastic elastomer
or a vulcanized olefinic elastomer. When the styrenic thermoplastic
elastomer is mixed with the base resin, the elastic recovery of the
elastic infill can be improved. The vulcanized olefinic elastomer
can contribute to an improvement in the heat resistance of the
elastic infill.
[0042] In some embodiments, the amounts of the ORC, the OBC, and
the rubber in the base resin may be appropriately determined taking
into consideration various factors, such as extrusion workability,
heat resistance, and elastic recovery. For example, the amount of
the rubber may be determined from the viewpoint of economic
efficiency and performance. The rubber is preferably used in an
amount of 5 to 50 parts by weight, based on 100 parts by weight of
the olefin copolymer.
[0043] The elastomer composition may further include a processing
aid. The processing aid may be polybutene or a process oil, which
improves the processability of the mixed compound and prevents an
increase in hardness when a large amount of the inorganic filler is
added, achieving improved flexibility. The processing aid is added
in an amount of 2 to 500 parts by weight, preferably 10 to 200
parts by weight, based on 100 parts by weight of the base resin. If
the content of the processing aid is less than the lower limit
defined above, flowability may be insufficient during processing.
Meanwhile, if the content of the processing aid is more than the
upper limit defined above, there may be a risk of bleeding.
[0044] The processing aid may be polybutene that is highly
compatible with the olefinic resin. This compatibility prevents the
migration of the low molecular weight polybutene or eliminates the
risk of bleeding of the polybutene in water, making the use of the
polybutene environmentally friendly. It is preferred that the
polybutene has a molecular weight of 300 to 8,000. The process oil
may be a mineral oil, such as a paraffinic or naphthenic oil.
[0045] The elastomer composition may further include a resin
stabilizer for the purpose of preventing the physical properties
and color of the elastomer from changing after construction in
artificial turf. For example, the resin stabilizer may be a thermal
stabilizer, an antioxidant or a UV stabilizer. The resin stabilizer
may be used in an amount of 0.01 to 10 parts by weight, based on
100 parts by weight of the base resin. If the resin stabilizer is
used in an amount of less than 0.01 parts by weight, its effect is
substantially negligible. Meanwhile, it is not economically
feasible to use the resin stabilizer in an amount of more than 10
parts by weight, considering its effectiveness.
[0046] The thermal stabilizer is based on tin, lead, cadmium or
zinc, preferably based on less harmful zinc. The antioxidant may be
an amine-, phenol- or phosphorus-based. The UV stabilizer may be
benzophenone-, benzotriazole- or hindered amine-based.
[0047] The elastomer composition may further include a pigment.
Black waste tire rubber chips strongly absorb sunlight, which is a
cause of temperature rise. The use of the pigment allows the
elastic infill to have a variety of colors. For example, the
pigment may be of the same color (i.e. green) as artificial turf.
Taking efficiency into consideration, it is preferable that the
amount of the pigment is within a range, 0.1 to 4 parts by weight,
based on 100 parts by weight of the base resin.
[0048] The elastic infill has a rebound resilience of at least 50%,
usually 50 to 60%, as tested according to ASTM D2632. If the
rebound resilience of the elastic infill is lower than 50%, the
rebound of a football may be below the standard. Meanwhile, if the
rebound resilience of the elastic infill exceeds 60%, large impacts
may be applied to the soles of players' feet during their play, and
hence, the players may be injured or tend to feel tired.
[0049] The elastic infill has a compression set of 2 to 20% or 5 to
15% at room temperature and 15 to 40% or 20 to 35% at 70.degree.
C., as measured based on ASTM D395. Due to its low compression set,
the elastic infill can maintain its original shape for a long
period of time and is prevented from agglomerating even at high
temperatures in summer.
[0050] The cross-linking of the olefin copolymer can contribute to
a marked improvement in the heat resistance of the elastic infill.
Particularly, the use of the inexpensive olefin random copolymer as
the base resin enables the production of the elastic infill with
high quality in an economical manner despite its poor heat
resistance. General artificial turf constructed on playgrounds is
heated (reportedly to a maximum of 70.degree. C.) in the middle of
summer, resulting in softening or melting and agglomeration of
infills. In severe cases, this agglomeration leads to caking. Such
a problem can be solved by using the elastic infill of the present
invention.
[0051] According to one embodiment, the elastic infill may be
produced by extrusion and pelletization of the elastomer
composition.
[0052] The elastic infill can be produced by the following method.
First, an elastomer composition including a silane coupling agent
and a mixture of an olefin copolymer-containing base resin and an
inorganic filler is provided. The elastomer composition, the silane
coupling agent, the inorganic filler, the base resin, and the
olefin copolymer are the same as those described above. The
elastomer composition may further include at least one additive
selected from the group consisting of initiators, catalysts,
processing aids, resin stabilizers, and pigments, which are also
the same as those described above.
[0053] Next, the elastomer composition is kneaded using a suitable
kneader, such as an open roll or kneader mixer, for example, after
kneaded at a temperature of 130 to 160.degree. C., the elastomer
composition is discharged from the kneader at a temperature of 140
to 170.degree. C.
[0054] Subsequently, the kneaded elastomer composition is extruded
and pelletized to obtain the desired elastic infill. A general
extruder, for example, a Banbury kneader, a Buss kneader, a single
screw extruder or a twin screw extruder may be used to extrude the
elastomer composition. The extrusion may be performed, for example,
in the temperature range of 90 to 170.degree. C. During the
extrusion, the silane coupling agent is chemically bound to the
base resin to form a silane grafted copolymer.
[0055] When extruded at a high temperature, the elastomer
composition is automatically cut to a particle size of 0.5 to 3 mm
in a hot cutting or underwater cutting mode by a die mounted on a
compression head of the extruder. As a result, the elastomer
composition can be produced into chips in the shape of elliptical
or circular pellets with an average size of 0.5 to 3 mm.
[0056] In one preferred embodiment, the method further includes
heating the pelletized elastic infill in water to cross-link the
elastic infill. For example, the cross-linking may be performed in
water at 70 to 90.degree. C. for 3 to 5 hours.
[0057] In one preferred embodiment, the method further includes
allowing the pelletized elastic infill to stand under ambient
conditions to cross-link the elastic infill. In this embodiment,
the pelletized elastic infill may be cross-linked slowly by the
reaction of the silane coupling agent with water in air.
[0058] Unlike waste tire chips produced by pulverization, the
elastic infill of the present invention has a uniform size and a
pellet shape after extrusion, which makes it possible that the
elastic infill of the present invention produces no dust, has high
heat resistance and elasticity, is not harmful to humans, and
causes no environmental problems. In addition, the elastic infill
of the present invention is economically advantageous because of
its low price.
[0059] The present disclosure will be explained in more detail with
reference to the following examples. However, these examples are
not intended to limit the scope of the present disclosure and
various modifications can be made thereto without departing from
the spirit and scope of the present invention as set forth in the
appended claims.
EXAMPLES
[0060] Waste tire chips: Threads were peeled from waste tires
(1.0-3.0 mm, CTCR 01, Cryotech, Korea) and pulverized at
-200.degree. C. to produce chips.
Comparative Examples 1-4
[0061] Elastomer compositions were prepared as shown in Table 1.
Each of the compositions was kneaded in a kneader under pressure at
120.degree. C., discharged at 150.degree. C., transferred to a
hopper of a twin screw extruder, and pelletized to a diameter of 2
mm by a rotary knife rotating at 150 rpm attached to an underwater
cutting die of the extruder set at 160.degree. C. to produce an
elastic infill for artificial turf. The elastic infill was placed
in a 10 mm thick mold, heated at 150.degree. C. for 5 min, cooled
to room temperature, and measured for rebound resilience and
compression set.
Examples 1-7
Elastomer Compositions were Prepared as Shown in Table 1
[0062] Each of the compositions was kneaded in a kneader under
pressure at 120.degree. C., discharged at 150.degree. C.,
transferred to a hopper of a twin screw extruder, and pelletized to
a diameter of 2 mm by a rotary knife rotating at 150 rpm attached
to an underwater cutting die of the extruder set at 160.degree. C.
to produce an elastic infill for artificial turf. The elastic
infill was placed in a 10 mm thick mold, heated at 150.degree. C.
for 5 min, cooled to room temperature, cross-linked in water at
60.degree. C. for 24 h, and measured for rebound resilience and
compression set.
[0063] The following base resins and silane coupling agent were
used.
[0064] EVA-1: Ethylene vinyl acetate copolymer (VA: 33%, MI: 13,
hardness: 63, Hanwha EVA 1833, Hanwha Chemical)
[0065] EAO-1: Ethylene alpha olefin copolymer (density: 0.863, MI:
0.5, hardness: 63, Engage 8180, Dow Chemical)
[0066] OBC-1: Olefin block copolymer (density: 0.877, MI: 5.0,
hardness: 60, Infuse D9507, Dow Chemical)
[0067] SEBS-1: Styrene ethylene butylene styrene (density: 0.89,
MI: 3.0, hardness: 67, Tuftec H1052, Asahi Kasei)
[0068] Silane-1: Vinyltrimethoxysilane
[0069] The physical properties of the elastic infills produced in
Comparative Examples 1-4 and Examples 1-7 are shown in Table 1.
TABLE-US-00001 TABLE 1 Com- Com- Com- Com- parative. parative.
parative. Ex- Ex- Ex- Ex- Ex- Ex- Ex- parative Waste Example
Example Example ample ample ample ample ample ample ample Example
tire 1 2 3 1 2 3 4 5 6 7 4 EVA-1 100 100 50 80 100 100 EAO-1 100
100 50 80 OBC-1 100 SEBS-1 100 20 20 Calcium carbonate 200 200 200
200 200 200 200 200 200 200 200 (CaCO.sub.3) Polybutene 50 50 50 50
50 50 50 50 50 50 Paraffin oil 50 Benzoyl peroxide 0.5 0.5 0.5 0.5
0.5 0.5 0.5 0.5 (BPO) Silane-1 2.0 2.0 2.0 2.0 2.0 2.0 1.0 0.4 DBTL
0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Antioxidant 1.0 1.0 1.0 1.0 1.0 1.0
1.0 1.0 1.0 1.0 1.0 UV absorber 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.0 1.0 Hardness Shore A 55 55 55 55 56 56 55 55 56 56 55 55
Rebound resilience 55 40 45 55 52 52 53 51 53 54 50 45 Compression
set 10 30 28 11 10 8 5 9 11 10 15 27 (r.t., ASTM D395, %)
Compression set 20 100 95 25 30 26 20 28 28 25 35 70 (70.degree.
C., ASTM D395, %) Evaluation of Good Very Very Good Good Good Good
Good Good Good Good Poor agglomeration poor poor when loaded at
70.degree. C. Dust Ob- Not Not Not Not Not Not Not Not Not Not Not
served observed observed observed ob- ob- ob- ob- ob- ob- ob-
observed served served served served served served served Overall
Poor Poor Poor Good Good Good Good Good Good Good Good Poor
performance judgement Suitability as infill Un- Un- Un- Un- Suit-
Suit- Suit- Suit- Suit- Suit- Suit- Un- suitable suitable suitable
suitable able able able able able able able suitable (expen-
sive)
[0070] The rebound resilience of each elastic infill was tested
according to ASTM D2632. The elastic infill was judged to be "good"
when the rebound resilience was .gtoreq.50% and "poor" when
<50%.
[0071] The compression set of each elastic infill was tested
according to ASTM D395. The elastic infill was judged to be "good"
when the compression set at room temperature was <25% and "poor"
when .gtoreq.25%. The elastic infill was judged to be "good" when
the compression set at 70.degree. C. was <40% and "poor" when
>40%.
[0072] The degree of agglomeration of each elastic infill was
evaluated when the elastic infill was loaded at a high temperature.
To this end, 1,000 g of the sample was put in an envelope made of
nylon cloth (20 cm (w).times.20 cm (l)) and introduced into an oven
at 70.degree. C. A stainless steel plate (1,000 g) having a size of
15 cm (d).times.7 mm (t) was placed on the sample. After heating
for 24 h, the sample was withdrawn from the oven. Some of the
infill particles in the nylon envelope were observed to
agglomerate. The agglomerations were collected and weighed. The
infill was judged to be "good" when the weight of
the-agglomerations was <30 g, "poor" when .gtoreq.30 g, and
"very poor" when .gtoreq.900 g.
[0073] Each infill sample was constructed in artificial turf (1
m.times.1 m). After a football was dropped from a height of 1 m
onto the artificial turf, the occurrence of dust from the
artificial turf was observed with naked eyes.
[0074] As can be seen from the results in Table 1, the elastic
infills produced by cross-linking of the ethylene copolymers in
Examples 1-7 were found to have at least 60% lower high-temperature
compression sets than those produced in Comparative Examples 1 and
2, demonstrating their higher elastic recovery. The elastic infills
of Examples 1-7 are inexpensive compared to the elastic infill
produced using SEBS in Comparative Example 3. In addition, the
elastic infill of Examples 1-7 underwent less agglomeration even
when loaded at 70.degree. C., revealing their better heat
resistance. Therefore, the elastic infills of Examples 1-7 are
suitable for use in artificial turf.
[0075] The waste tire chips produced a large amount of dust to
cause pollution when struck with a football. When the waste tire
chips were continuously exposed to sunlight under an ambient
atmosphere at 30.degree. C., their surface temperature increased to
70.degree. C. Such problems were not encountered in the inventive
elastic infills. In conclusion, the inventive elastic infills can
provide a comfortable exercise environment for players.
* * * * *